What is\FileSystem\srvnet anyway, and how can I allow my computer to go to sleep automatically?

Disabling Wake-On-LAN from device manager didn't change anything, but disabling the network adapter and then re-enabling it did. The SMB over TCP/IPv6 link-local connection at the end vanished, and powercfg -requests showed no issues preventing sleep mode. Unfortunately, after a few moments the connection pair reappeared, this time using the IPv6 loopback address:

TCP [::1]:445 [::1]:49401 ESTABLISHED 4
Can not obtain ownership information
TCP [::1]:49401 [::1]:445 ESTABLISHED 4
Can not obtain ownership information

Now disabling the network adapter doesn't help anymore, but stopping the Workstation service did. Why would the system establish an SMB connection to itself?